Halogenated hydrocarbon compounds include the family of compounds of bromo-, fluoro- and/or chloro-ethers, fluorinated alkyl ethers, chlorofluorocarbons and chlorofluoro ethers and their derivatives. This family of compounds are typically used as solvents, refrigerants, anesthetic gases, aerosol propellants, blowing agents and the like. Many of these compounds are widely used and normally discharged into the atmosphere. However, if these compounds could be recovered and re-used there would be a considerable cost saving and reduction in environmental pollution. In view of the possible effects of released anesthetic gases, attempts have already been made to recover such gases.
An example of anesthetic gas removal, is with regard to patient exhalent to ensure that the environment in the operating theatre does not contain anesthetic gases which can have a long term effect on the professionals conducting the operation. Commonly, anesthetic gases are removed from patient exhalent by use of various types of disposable absorbers, such as that disclosed in U.S. Pat. Nos. 3,867,936 and 3,941,573. In the U.S. Pat. No. 3,867,936 to Kelley, an absorber unit is in the shape of a hollow drum filled with activated carbon to absorb anesthetic gases exhaled by the patient. When the weight of the absorber unit increases to a predetermined value, the unit is replaced with a fresh one. In Chapel, U.S. Pat. No. 3,941,573, a molecular sieve is used in combination with the activated carbon in a disposable cartridge. The cartridge is included in the patient anesthetic administration breathing system to absorb on both the activated carbon and the molecular sieve materials the exhaled anesthetic gases.
It is common to dispose of the absorber units used to absorb anesthetic gases. However, in view of the rising costs of the anesthetic gases, attempts are being made to recover them. For example, in U.S. Pat. No. 3,592,191, a system is provided for recovering exhausted anesthetic gases from patient exhalent by removing water vapor from the collected gases by their condensation thereof or with a hygroscopic material. This treated gas then has the anesthetic agent extracted therefrom by a cryogenic process in which the vapors of the anesthetic gases are condensed to liquid phase, or by removal on an absorbent material which is processed later to remove the anesthetic agents. The collected anesthetic liquids are then reintroduced directly into the anesthetic system. Such approach has little if any facility to control bacterial contamination and recycle of harmful microorganisms to the patient.
Another approach in the recapture of anesthetic gases is disclosed in Czechoslovakian patent 185,876. An adsorbent material is used to adsorb halogenous inhalant anesthetics from the patient exhalent. When the adsorbent material is saturated, it is removed in an appropriate container and placed in a regeneration system. A purging gas, such as steam, is used to remove the anesthetic agents from the adsorbent material. The purged gas is then collected with water removed therefrom and the separated anesthetic agents are subjected to fractionation to separate out the individual anesthetic agents from the supply of anesthetic gases from various operating theatres.
The use of molecular sieves to adsorb gaseous components is exemplified in U.S. Pat. No. 3,729,902. Carbon dioxide is adsorbed on a molecular sieve which is regenerated with heated steam to remove the carbon dioxide from the adsorbent material. Another example of the use of molecular sieves to adsorb organic materials is disclosed in Canadian patent 1,195,258. In this instance, a hydrophobic molecular sieve is used to adsorb organic species from a gas stream containing moisture. The hydrophobic molecular sieve selectively adsorbs the organic molecular species into the adsorbent material, while preventing the collection of water vapor from the gas stream on the adsorbing material. The temperature and pressure at which the system is operated is such to prevent capillary condensation of the water in the gas stream onto the adsorbing material. By removing the adsorbing material from the system, the adsorbing material is essentially free of water yet has absorbed thereon the desired organic molecular species. The organic molecular species are then recovered from the adsorbent material by purging.
Particularly desirable types of anesthetic gases are commonly sold under the trade marks ETHRANE and FORANE, as disclosed in U.S. Pat. Nos. 3,469,011; 3,527,813; 3,535,388; and 3,535,425. These types of anesthetic gases are particularly expensive; hence an effective method of recovering them from patient exhalent for reuse would be economically advantageous.